Two temperature refrigerator system



July 6, 1954 R. CLARK ET AL TWO TEMPERATURE REFRIGERATOR SYSTEM Filed Feb. 7, 1952 o o o o o OOOOOOOOOOGOOOO a J[3'2 E liz/ntanf' Mana Clark aiiarles l zZae% PO44Q daffy Patented July 6, 1954 TWO TEMPERATURE REFRIGERATOR SYSTEM Adna H. Clark and Charles E. Sulcek, Evansville,

Ind., assignors to International Harvester Company, a corporation of New Jersey Application February 7, 1952, Serial No. 270,485

7 Claims.

This invention relates generally to refrigeration apparatus and more particularly to a multiple temperature refrigeration system.

Recently developed refrigerated cabinets are generally provided with a fast freezing compartment and a food storage compartment. The fast freezing compartment is adaptable for the storage of frozen foods, ice cubes and other articles which are to be maintained at low temperatures. It has been found that the fast freezing compartment should be maintained at approximately F. in order to retain the articles therein in the frozen state. The food storage compartment should be maintained at approximately 37 F. so that the food articles stored therein will be properly preserved. These two compartments -may be cooled by separate evaporators and in such case, it is necessary to operate the evaporators at different temperatures in order to cool the compartments to the desired temperature. Accordingly, it is an object of the presentinvention to provide a refrigeration system having separate evaporators which will be maintained at different operating temperatures.

Another object of the invention is to provide a refrigeration system which is charged with Another object of the invention is to provide a refrigeration system which is adaptable for cooling two separate compartments of a refrigerated cabinet to different temperatures.

Another object of the invention is to provide an improved two-temperature refrigeration system which operates efficiently to cool a refrigerated cabinet.

The invention itself, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment, when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of a refrigeration system embodying the invention.

Fig. 2 is a sectional view of the separator taken along line 22 of Fig. 1.

Referring now to the drawings for a detailed description of the invention, a refrigerator cabinet ID- is shown in section in Fig. 1. As illustrated, the cabinet [0 comprises an outer shell I I having an inner shell l2 spaced therein with insulating material l3 disposed therebetween whereby the heat leakage between the two shells will be reduced substantially the space enclosed by the inner liner I2 is divided by an insulating partition l4 into a low temperature compartment I5 and into a food storage compartment l 6. The cabinet H! as illustrated is arranged and constructed as a domestic type refrigerator, but it is to be understood that the cabinet could be constructed in other forms, since the present invention is directed to the refrigeration system and not to the refrigerated cabinet.

The refrigeration system is diagrammatically illustrated in the drawings, and as seen in Fig. 1, comprises two heat exchange units or evaporators IT and IS. The evaporator I? is positioned within the freezing compartment l 5 and is illustrated in the form of a coil or conduit which is bent into a series of runs or turns. The evaporator I8 is illustrated in the same form as the evaporator l1 and is positioned within the lower compartment 16. The evaporators ll and It are preferably secured in heat exchange relation to the walls of the inner liner 12 so that the walls of the compartments l5 and It will be cooled thereby. The outlet end IQ of the evaporator IT connects to an accumulator 2c and a suction tube 2| connects the outlet of the accumulator 2a to the inlet 22 of a motor-compressor unit 23. A second accumulator 24 is connected to the suction tube 2| by conduit 25 and the outlet end 26 of the evaporator l8 connects into this accumulator.

The motor-compressor unit 23 may comprise an electric motor and'piston type compressor hermetically sealed within an outer casing in the manner common to the art. The outlet 27 of the unit 23 is connected by conduit 28 to a condenser 29 which ispreferably arranged so that cooling air will circulate thereover. A second condenser 30 is connected to the condenser 29 by a separator 31 which comprises an inner tube 32 and a cylindrically shaped outer casing 33. The inner tube 32 extends through the central portion of the outer casing 33 with the ends thereof connected to the condensers 29 and 3B. The

horizontally disposed straight portion 34 of the tube 32 which is located within the casing 33 is provided with a series of apertures or vertically extending holes 35 through the lowermost portion thereof as seen in Fig. 2. The holes 35 will permit any liquid flowing through the tube 32 to drain into the casing 33 as will be explained hereinafter.

The casing 33 is provided with an opening therethrough in which one end of a conduit 36 is secured. The other end of the conduit 36 is connected to a filter element 3i and the outlet of the filter 31 is joined to a restrictor or capillary tube 38 which extends upwardly and is provided with several turns 39 whereby a tube of considerable length may be fashioned into a compact coil. The upper end of the capillary tube 38 is joined to the inlet end 49 of the exaporator IS. The inlet of a second filter 4| is joined to the outlet of the condenser se by a short conduit 42, and the outlet of the filter 4! is connected to the inlet 43 of evaporator I? by a second capillary or restrictor tube M having several turns 45 fashioned into a compact coil.

The construction of the invention having been described, the operation of the invention will now be explained. As previously mentioned, the two compartments 1% and R6 are to be maintained at different temperatures. Compartment l should be maintained at approximately 10 F. so that ice cubes may be frozen therein and frozen foods may be stored therein. The compartment I6 is normally used for the preservation of food articles and should be maintained at approximately 37 F. To properly cool these compartments, it is necessary to operate the evaporators H and H3 at different temperatures.

The refrigeration system illustrated is charged with a mixture of two refrigerants having different boiling points. While various types of refrigerants may be used to provide this mixture, by way of example, two refrigerants are used, one being dichlorodifiuoromethane, commonly called (I -12), and the other being sulphur dioxide, commonly designated (S02). The (S02) has a lower vapor pressure than the (F l2)fand will condense at a higher temperature. After being compressed by the motor-compressor unit 23, the mixture of refrigerant gases is conveyed by conduit 28 to the condenser 29. As the gaseous mixture progresses through the condenser 29, it will be cooled to a lower temperature by the cooling air circulating thereover. Since the ($02) will condense at a higher temperature than the (F42), it will be liquefied in condenser 29.

whereas the (2 12) will still be in the gaseous state after its journey through the condenser. As the mixture of (S02) liquid and (F -12) gas passes through the straight portion 34 of the tube 32, the (S02) liquid will collect in the lower portion of the tube 32 and drain through the holes 35 into the casing The (F42) gas will be passed through the upper portion of the tube 32 into condenser 39 where it will be cooled and condensed by cooling air circulating over the outer surfaces of the condenser.

From the casing 33, the liquefied (S02) is conveyed by conduit 353 through filter 31 where any foreign matter will be removed therefrom, then metered by capillary tube 38 into the evaporator 13. Assuming that the motor-compressor 23 is operating with an inlet pressure of 9.2 lb./sq. in. gage, the (S02) will vaporize at a temperature of 34 within the evaporator 18. This will maintain the temperature of compartment H5 at the desired temperature of 37 F. The liquefied (F-12) will be conveyed from condenser 30 through filter 4| where foreign matters will be removed therefrom, then metered by capillary tube 44 into the evaporator I1. Since the evaporators l1 and [8 are connected to the inlet of compressor unit 23 by a common suction tube 2|, they will both be subjected to the same 9.2 lb./sq. in. gage pressure. The (F-12) within the evaporator, having a lower boiling point than S02, will vaporize at a temperature of 0 F. and will cool the low temperature compartment IE to approximately 10 F. The (F-12) vapor will then pass through the accumulator 21! into the suction tube 2| and be remixed with the (S02) vapor which is conveyed from the evaporator l8 through the accumulator 24 into the suction tube 2|. The accumulators 2&3 and 24 will prevent liquid refrigerant from being drawn into the suction tube 2 l. The refrigerant vapors will then be pulled through the suction tube 2| by the motor-compressor unit 23 and be recompressed thereby after which they will be recirculated through the refrigeration system.

From the foregoing it is readily seen that a refrigeration system is provided which will operate to maintain separate compartments of a refrigerated cabinet at different temperatures. Automatic means for controlling th operation of the motor-compressor unit 23 in response to the temperature within the cabinet Ill ma be provided if desired. The filters 3! and 4! and the accumulators 2i] and 24 may be selected from the many types readily available on the present market. As will be apparent to those skilled in the art, the refrigeration system illustrated and described is simple in structur and efficient in operation. As compared with the two-temperature refrigeration systems common in the art, the present invention provides a system comprising a minimum number of parts. The system is illustrated diagrammatically but it is to be understood that it could be compactly arranged and positioned within a small machinery compaitment provided within the cabinet Ill.

Although only a preferred form of the invention has been illustrated, and that form described in detail, it will be apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

1. In a refrigeration system, a pair of evaporators connected in parallel to the inlet of a compressor, a first condenser and a second condenser connected in series to the outlet of said compressor, said system being charged with a first refrigerant and a second refrigerant which has a lower boiling point than said first refrigerant, means for separating said first refrigerant from said second refrigerant after it has been liquefied by said first condenser, means for metering said liquefied first refrigerant into one of said evaporators, and means for metering said second refrigerant into said other evaporator after it has been liquefied by said second condenser.

2. In a refrigeration system, a first evaporator and a second evaporator connected in parallel to the inlet of a compressor, a first condenser and a second condenser connected in series to the outlet of said compressor, said system being charged with two refrigerants having different boiling points, a separator connected between said condensers, the refrigerant having the higher boiling point being liquefied by said first condenser and then collected by said separator, means for metering the liquefied refrigerant from said separator into said first evaporator, and means for metering said other refrigerant into said second evaporator after it has been liquefied by said second condenser.

3. In a refrigeration system, a first evaporator and a second evaporator connected in parallel to the inlet of a compressor, a first condenser and a second condenser connected in series to the outlet of said compressor, said system being charged with two refrigerants having different boiling points, the outlet of said first condenser being connected to the inlet of said second condenser by a tube having apertures through the lower portion thereof, an outer casing surrounding said tube, the refrigerant having the higher boiling point being liquefied by said first ccndenser and then drained through said apertures into said casing, means for metering the liquefied refrigerant from said casing into said first evaporator, and means for metering said other refrigerant into said second evaporator after it has been liquefied by said second condenser.

4. In a refrigeration system, a pair of evapora tors connected in parallel to the inlet of a compressor, liquefying means connected to the outlet of said compressor, said system being charged with two refrigerants having different boiling points, means for conveying said refrigerants through a separator after they have been cooled to a temperature between the boiling points of said refrigerants by said liquefying means, the refrigerant having the higher boiling point being collected by said separator, means for conveying the refrigerant collected by said separator to one of said evaporators, and means for conveying said other refrigerant from said separator through said liquefying means so that it is fully liquefied, then conveying it into the other of said evaporators.

5. In a refrigeration system, a first evaporator and a second evaporator connected in parallel to the inlet of a compressing means, liquefying means connected to the outlet of said compressingmeans, said system being charged with a first refrigerant and a second refrigerant which has a lower boiling point than said first refrigerant, means for conveying the refrigerants through a separator after said first refrigerant has been liquefied by said liquefying means but before said second refrigerant has been liquefied, said separator comprising a casing which surrounds an inner tube through which said refrigerants are conveyed, said inner tube being provided with apertures in the lower portion thereof through which said first refrigerant drains into said casing, means for conveying said first refrigerant from said casing into said first evaporator, and means for conveying said other refrigerant from said separator through said liquefying means so that it is fully liquefied, then conveying it into the other of said evaporators.

6. In a refrigeration system, a first evaporator and a second evaporator connected in parallel to the inlet of a compressor, liquefying means connected to the outlet of said compressor, said system being charged with a first refrigerant and a second refrigerant which has a lower boiling point than said first refrigerant, means for conveying the refrigerant through a separator after said first refrigerant has been liquefied by said liquefying means but before said second refrigerant has been liquefied, means for conveying said first refrigerant from said separator into said first evaporator, and means for conveying said second refrigerant from said separator through said liquefying means so that it is fully liquefied, then conveying it into said second evaporator.

'7. Refrigerating apparatus comprising a cabinet having two separate compartments, each compartment being provided with an evaporator which is connected in parallel to the inlet of a compressor, a liquefying means connected to the outlet of said compressor, said system being charged with a first refrigerant and a second refrigerant which has a lower boiling point than said first refrigerant, means for conveying the refrigerants through a separator after said first refrigerant has been liquefied by said liquefying means but before said second refrigerant has been liquefied, means for metering said first refrigerant from said separator into one of said evaporators, and means for conveying said second refrigerant from said separator through said liquefying means so that it is fully liquefied, then metering it into the other of said evaporators,

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 1,806,498 Randel May 19, 1931 2,133,962 Shoemaker Oct. 25, 1938 2,233,414 Hubacker Mar. 4, 1941 2,403,220 Hintze July 2, 1946 

